2019-09-19 14:43:19 +00:00
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From 0c6190fa3cfeafd773b51b751a473d6775c23309 Mon Sep 17 00:00:00 2001
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2019-08-09 17:50:30 +00:00
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From: P33M <2474547+P33M@users.noreply.github.com>
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Date: Wed, 14 Aug 2019 14:35:50 +0100
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2019-12-23 12:42:55 +00:00
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Subject: [PATCH] dwc_otg: use align_buf for small IN control transfers
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2019-08-09 17:50:30 +00:00
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(#3150)
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The hardware will do a 4-byte write to memory on any IN packet received
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that is between 1 and 3 bytes long. This tramples memory in the uvcvideo
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driver, as it uses a sequence of 1- and 2-byte control transfers to
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query the min/max/range/step of each individual camera control and
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gives us buffers that are offsets into a struct.
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Catch small control transfers in the data phase and use the align_buf
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to bounce the correct number of bytes into the URB's buffer.
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In general, short packets on non-control endpoints should be OK as URBs
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should have enough buffer space for a wMaxPacket size transfer.
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See: https://github.com/raspberrypi/linux/issues/3148
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Signed-off-by: Jonathan Bell <jonathan@raspberrypi.org>
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---
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drivers/usb/host/dwc_otg/dwc_otg_hcd.c | 18 ++++++++++++++++++
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1 file changed, 18 insertions(+)
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--- a/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
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+++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
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@@ -1182,6 +1182,7 @@ static void assign_and_init_hc(dwc_otg_h
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dwc_otg_qtd_t *qtd;
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dwc_otg_hcd_urb_t *urb;
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void* ptr = NULL;
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+ uint16_t wLength;
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uint32_t intr_enable;
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unsigned long flags;
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gintmsk_data_t gintmsk = { .d32 = 0, };
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@@ -1293,6 +1294,23 @@ static void assign_and_init_hc(dwc_otg_h
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break;
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case DWC_OTG_CONTROL_DATA:
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DWC_DEBUGPL(DBG_HCDV, " Control data transaction\n");
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+ /*
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+ * Hardware bug: small IN packets with length < 4
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+ * cause a 4-byte write to memory. We can only catch
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+ * the case where we know a short packet is going to be
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+ * returned in a control transfer, as the length is
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+ * specified in the setup packet. This is only an issue
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+ * for drivers that insist on packing a device's various
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+ * properties into a struct and querying them one at a
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+ * time (uvcvideo).
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+ * Force the use of align_buf so that the subsequent
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+ * memcpy puts the right number of bytes in the URB's
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+ * buffer.
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+ */
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+ wLength = ((uint16_t *)urb->setup_packet)[3];
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+ if (hc->ep_is_in && wLength < 4)
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+ ptr = hc->xfer_buff;
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+
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hc->data_pid_start = qtd->data_toggle;
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break;
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case DWC_OTG_CONTROL_STATUS:
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